Electric motors, for instance, asynchronous motors running on three-phase current, are frequently designed so as to be “self-ventilating”. For this purpose, a ventilator is attached to the drive shaft and supplies the motor with cooling air. This ventilator usually includes a radial fan, but in rare cases, an axial fan is provided that is mounted on one end of the drive shaft, the so-called B-side of the electric motor, and rotates below a fixed ventilator cowl that is attached to the motor housing. The cowl guides the stream of cooling air into the axial cooling ribs of the motor housing so as to achieve an optimal cooling effect. Thus, the motor housing is cooled from its outside.
For many applications, electric motors must drive both a number of machines and also accessory ventilators for the assembly. The accessory ventilators supply cooling air to, for example, the machine sets that are being driven by the motor.